This invention relates to an electromotive scooter which gets its driving force from an electric motor driven by batteries mounted thereon, or more particularly to a power source unit for an electromotive scooter and a warning device which tells or warns the rider and near-by people when the switch of the electric motor is on and the scooter is ready to run.
The primary object of the invention is to provide a power source unit for an electromotive scooter which supplies power of nominal value of 48V to the electric motor that requires high voltage to exert high driving performance and also supplies power of nominal value of 12V via an auxiliary power source to the other electric devices in such a manner that even in a case of large fluctuation of voltage in the main power source, a stable power is assured for said electric devices, a control unit, for example, making it possible to employ as these devices those products for common use on the market.
The electric equipment on an electromotive scooter can be generally divided into three categories: the driving unit (electric motor), the control unit and the lighting devices. In the conventional scooters, it is a general practice to supply for these units or devices power of the same voltage from a common power source; no auxiliary power source is provided and all the units and devices are directly connected to storage batteries mounted in a place. One of the results thereof is that electromotive scooters are very poor in the driving performance compared with usual scooters equipped with internal combustion engines. One of the causes of it comes from the restriction on power source units. As stated above, all the devices and units on a conventional scooter have a common power source and, since most of the parts of the lighting devices on the usual market such as lamps and relays are manufactured for nominal voltage of 12V or 24V, adoption of these parts necessitates restriction of voltage of the power source to 12V or 24V. This results in a restriction of the output power of the driving unit (electric motor) itself and an inferior driving performance compared with the internal combustion engine scooters and has prevented electromotive scooters from coming into a wide use. On the other hand, in contrast to in-yard electromotive vehicles such as forklifts and golf carts which also use storage batteries as power source, electromotive scooters have a characteristic that a high rate discharge is required and has a large fluctuation in voltage of the power source; when the storage batteries are near exhaustion or a big current is discharged for acceleration or hill-climbing, the voltage drops greatly. This voltage drop has been a source of many troubles such as a decrease of illumination of lighting devices and, in case of an extreme drop, a malfunction of the control unit and hence a deteriorated action of tile driving unit.
The second object of the invention is to prevent accidents peculiar to the electromotive scooters, or in other words, to provide a warning device which, by means of a pilot lamp that gives a visual signal and a warning sound that gives an acoustic signal as an equivalence of the sensation of idling of internal combustion engines, tells or warns the rider or nearby people when the switch for the electric motor is on and the vehicle is ready to run, and thereby assure safety and prevent the vehicle from being left in an active condition.
The conventional internal combustion engine scooter comes into a ready-to-run condition as the engine is started, and even in halted condition, keeps what is called the idling condition in which the inner combustion engine rotates at a low revolution; therefore the rider or nearby people can clearly know through touch and sound of vibration from the engine that the vehicle is active. The electromotive scooter, however, does not have an idling condition like the internal combustion engine scooter. The motor makes rather a soft working sound and causes little vibration and further is in a completely stopped and still condition when the vehicle is not running. It is, therefore, difficult for the rider or nearby people to tell through senses if the scooter is in a condition ready to run or not. If, therefore, the throttle of an electromotive scooter is operated carelessly out of a habit with an internal combustion engine scooter, it may give rise to an accident through an abrupt starting. To avoid such an accident, a safety system wherein a switch built in the seat allows the motor to be started only when the rider is on the seat has been developed and put into practice. It is pointed out, however, that this safety measure has such drawbacks that the difference in sitting positions from rider to rider due to, for example, difference of size of their bodies may cause inaction of the motor or that lifting of the body weight above the seat by the rider while riding may cause dangerous sudden stops of the vehicle or intermittent loss of driving force.